System and method of slurry treatment

ABSTRACT

Wastewater streams from semiconductor processing operations are treated to reduce the concentration therein of one or more metal species to a satisfactory level. The disclosed systems and technique utilize complexing ion exchange media to treat the wastewater streams having a significant concentration of oxidizing species and high solids concentration.

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention relates to a system and method for reducing theconcentration of one or more metal species from a waste stream and, inparticular, to a system and apparatus for removing one or more metalspecies from chemical mechanical planarization waste slurry streams.

2. Discussion of Related Art

Techniques can be employed for reducing the concentration of the one ormore target species from a stream. For example, Medford et al., in U.S.Pat. No. 3,301,542, disclose a system for treating acidic etchingsolutions. Swanson et al., in U.S. Pat. No. 3,428,449, discloseextraction of copper from acidic liquors with a phenolic oxime. Spinney,in U.S. Pat. No. 3,440,036, discloses the recovery of copper fromcopper-bearing solutions. Stephens, in U.S. Pat. No. 3,912,801,discloses the solvent extraction of metals with a cyclic alklylenecarbonate. Koehler et al., in U.S. Pat. No. 3,914,374, disclose theremoval of residual copper from nickel solutions. Asano et al., in U.S.Pat. No. 3,923,741, disclose an acrylamide aqueous solution refiningprocess. Asano et al., in U.S. Pat. No. 3,941,837, further disclose amethod of treating an aqueous solution of acrylamide. Leach et al., inU.S. Pat. No. 4,010,099, disclose settlers for copper liquid extractionsystems. Etzel et al., in U.S. Pat. No. 4,210,530, disclose thetreatment of metal plating wastes with an unexpanded vermiculite cationexchange column. Dalton, in U.S. Pat. No. 4,231,888, discloses acomposition used for extracting copper from aqueous copper salts.Merchant et al., in U.S. Pat. No. 4,239,210, disclose a method ofregenerating etchant and recovering etched metal. Brown et al., in U.S.Pat. No. 4,666,683, disclose a process for removal of copper fromsolutions of chelating agent and copper. Gefvart, in U.S. Pat. No.5,256,187, discloses the separation of precious metals by an ionexchange process. Guess, in U.S. Pat. No. 5,298,168, discloses a ferrousdithionite process and composition for removing dissolved heavy metalsfrom water. Siefert et al., in U.S. Pat. No. 5,346,627, disclose amethod for removing metals from a fluid stream. Marquis et al., in U.S.Pat. No. 5,348,712, disclose the use of carbonates in metal ionextraction. Hayden, in U.S. Pat. No. 5,464,605, discloses a process forthe decomposition and removal of peroxides. Abe et al., in U.S. Pat. No.5,476,883, disclose a preparation process of acrylamide from purifiedacrylonitrile. Misra et al., in U.S. Pat. No. 5,599,515, disclose amethod of removing mercury from solution. Sassaman et al., in U.S. Pat.No. 6,315,906, disclose removing metal ions from wastewater. Filson etal., in U.S. Pat. No. 6,346,195, disclose the ion exchange removal ofmetals from wastewater. Kemp et al., in U.S. Pat. No. 6,818,129,similarly disclose the ion exchange removal of metal ions fromwastewater. However, Kemp et al., in U.S. Pat. No. 6,818,129, notes thatif hydrogen peroxide is present, it cannot be present with some resinsbecause of its incompatibility. Kemp et al. further note that ionexchange can be used to attach copper ions, but would not likely work ona polishing slurry stream because of the presence and amount of solidspresent therein, typically in the form of silica, alumina slurry.

SUMMARY OF THE INVENTION

In accordance with one or more embodiments, the invention is directed toa method of treating a slurry stream. The method can comprise steps ofproviding the slurry stream comprising at least one metal and at leastone oxidizer present at a concentration of at least about 50 mg/L andintroducing the slurry stream into an ion exchange column.

In accordance with one or more embodiments, the invention is directed toa method of treating a chemical mechanical polishing slurry stream. Themethod can comprise a step of introducing the slurry stream into atreatment system consisting essentially of at least one ion exchangeunit comprising a chelating ion exchange resin.

In accordance with further embodiments, the invention is directed to amethod for fabricating an electronic component. The method can comprisechemical mechanical polishing the electronic component with a slurry andintroducing at least a portion of the slurry to a treatment systemconsisting essentially of an ion exchange column comprising ion exchangematerial comprising an iminodiacetate functional group.

In accordance with one or more embodiments, the invention is directed toa treatment system for treating a slurry stream which can comprise atleast one metal selected from the group consisting of copper, lead,nickel, zinc, cobalt, cadmium, iron, manganese, and tungsten and atleast one oxidizing species selected from the group consisting of nitricacid, hydrogen peroxide, ferric nitrate, and ammonium persulfate presentat a concentration of at least about 50 mg/L. The treatment system cancomprise an inlet fluidly connected to a source of the slurry stream anda means for reducing the concentration of the at least one metal fromthe slurry stream.

In accordance with one or more embodiments, the invention is directed toa method of facilitating treatment of a slurry stream having at leastone metal species. The method comprises step of providing a treatmentsystem consisting essentially of an ion exchange column having ionexchange media contained therein. The ion exchange media comprises atleast one pendant functional group capable of forming a complex with theat least one metal species.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In thedrawings, each identical or nearly identical component that isillustrated in various figures is represented by a like numeral. Forpurposes of clarity, not every component may be labeled in everydrawing. In the drawing:

FIG. 1 is a schematic illustration of a treatment system in accordancewith one or more embodiments of the invention;

FIG. 2 is a schematic illustration of a treatment system in accordancewith one or more embodiments of the invention as described in Examples 1and 2;

FIG. 3 is a schematic illustration of a treatment system described inExamples 3 and 4;

FIG. 4 is a schematic illustration of yet another treatment systemdescribed in Example 5; and

FIG. 5 is a schematic illustration of a pretreatment system described inExample 6.

DETAILED DESCRIPTION

This invention is not limited in its application to the details ofconstruction and the arrangement of components set forth in thefollowing description or illustrated in the drawings. The invention iscapable of other embodiments and of being practiced or of being carriedout in various ways. Also, the phraseology and terminology used hereinis for the purpose of description and should not be regarded aslimiting. The use of “including,” “comprising,” “having,” “containing,”“involving,” and variations thereof herein, is meant to encompass theitems listed thereafter and equivalents thereof as well as additionalitems.

In accordance with one or more embodiments, the invention providessystems and techniques that remove, or at least reduce a concentrationof, metal ions from a solution or stream. In some cases, the processesand systems of the invention may be utilized to remove one or moreundesirable species, such as metal ions, from one or more fluid streams,typically one or more wastewater streams. In accordance with furtherembodiments, the invention provides systems and techniques that remove,or at least reduce the concentration of, one or more transition metalions from solutions and/or streams containing high amounts of suspendedsolids (also referred to herein as particulate material), such as slurrystreams. In some cases, the invention provides systems and techniquesthat remove, or at least reduce the concentration of, copper ions fromone or more slurry streams. For example, the processes and systems ofthe invention can remove copper ions, from a wastewater from a byproductpolishing slurry from chemical mechanical polishing (CMP) of integratedcircuits by attaching the metal ions or otherwise immobilizing the metalions thereby producing an environmentally clean discharge water product.The phrase “environmentally clean” refers to a wastewater dischargestream that can be directed to a municipal wastewater treatment plant,such that the wastewater discharge stream contains copper ions in aconcentration less than about 0.5 mg/L (about 0.5 ppm).

In accordance with still further embodiments, the treatment system andtechniques of the invention can comprise, consist essentially of, orconsist of, one or more ion exchange unit operations that can remove theone or more target species from the one or more slurry streams and canrender the one or more slurry streams suitable for discharge to theenvironment. In accordance with other embodiments, the treatment systemand techniques of the invention can comprise, consist essentially of, orconsist of an ion exchange subsystem and a carbon subsystem. The ionexchange system can utilize one or more ion exchange columns and thecarbon system can utilize one or more carbon beds. In accordance withyet further embodiments, the treatment systems and techniques of theinvention can utilize an ion exchange column, a carbon bed, or acombination thereof, without any unit operations that reduce orotherwise change a solids concentration of the slurry stream to betreated. The systems and techniques of the invention can treat a CMPslurry stream by utilizing an ion exchange column, a carbon bed, orcombination thereof, without substantially changing a solidsconcentration of the CMP slurry stream. As used herein, the phrase“without substantially changing” can refer to a concentration of solidsin the CMP slurry stream to be treated relative to a concentration ofsolids in the resultant, treated slurry stream, such that theconcentrations are the same or within about 5% or 10% because of solidsconcentration reduction associated with solids being unintentionallyretained in the treatment system.

As used herein, the phrase “suitable for discharge” refers to treatedstreams wherein the concentration of one or more regulated speciescontained therein is at a level not greater than government controlledor mandated limits. Thus, the systems and techniques of the inventioncan be utilized to facilitate fabrication of one or more semiconductordevices, and/or one or more types of semiconductor devices, bydelivering a dischargeable slurry stream that meets or exceeds one ormore imposed regulatory constraints. In accordance with one or moreembodiments, the systems and techniques of the invention can remove orat least reduce the concentration of one or more target metal species toa level or concentration that satisfies environmental discharge limitsand/or guidelines. In accordance with some aspects of one or moreembodiments of the invention, the disclosed systems and techniques cancomprise one or more treatment systems that comprises, in some cases,consists essentially of, one or more unit operations that contacts theslurry stream and removes therefrom one or more target species.

The systems and techniques of the invention can also be utilized toeffect concentration reduction of contaminants such as, but not limitedto, transition metals, from one or more streams comprising entrainedparticulate materials. Solids or particulate materials are definedherein using Standard Methods 2540 B, Total Solids Dried at 103-105° C.(1998, 20^(th) Ed.).

In accordance with one or more embodiments, the systems and techniquesof the invention removes metal ions such as, but not limited to coppermetal ions, from a wastewater stream such as a byproduct polishingslurry stream, from one or more chemical mechanical planarizationprocesses during fabrication operations directed to integrated circuitmicrochips devices.

Semiconductor manufacturing processes typically utilize one or moremetals such as, but not limited to, aluminum and/or transition metals,such as copper and tungsten, in one or more operations duringfabrication operations of microchip devices or components. Chemicalmechanical planarization or polishing is one technique that can beutilized during the fabrication operations of such devices. CMPoperations can be utilized to produce smooth surfaces on suchsemiconductor devices. Typical CMP processes utilize one or morepolishing slurries to facilitate the planarization process. Thepolishing slurry is typically used with a polishing pad to remove excessor undesirable metal material from the semiconductor device. To furtheror facilitate the planarization process, the polishing slurry typicallycomprises one or more abrasive materials and, in some cases, one or moreagents that facilitate the planarization process.

During the CMP process, silicon and other metals are typically removedfrom the semiconductor device and carried in a chemical mechanicalpolishing slurry stream. In particular, CMP planarization operationsperformed on copper-based microchip devices can produce a byproduct“grinding” (polishing) slurry wastewater stream which typicallycomprises a metal species, typically as ions, at a concentration rangingfrom about 1 mg/L to about 100 mg/L. A typical CMP tool can produce achemical mechanical slurry stream at a flow rate of about 10 gpm,typically including rinse streams. However, because fabricationfacilities typically operate a plurality of such tools, a sufficientquantity of one or more metals copper can be present in the aggregateslurry stream at a concentration, quantity, or volume that can representan environmental concern, if discharged without further treatment. Forexample, a multiple copper CMP tool cluster can generate about 100 gpmof wastewater.

The stream to be treated can comprise one or more oxidizers or oxidizingagents as an additive. The oxidizing agent can be any species thatfacilitates dissolution of the metal species, e.g., copper. For example,the oxidizing agent can be nitric acid, hydrogen peroxide (H₂O₂), ferricnitrate, and ammonium persulfate, as well as mixtures or combinationsthereof. Other, non-limiting examples of oxidizers or precursors includeiodates, periodates, bromates, perbromates, chlorates, perchlorates,peroxygen compounds, nitrate compounds, persulfate compounds,permanganate compounds, and chromate compounds. The oxidizing agent canbe present in the slurry stream at a concentration sufficient tofacilitate metal dissolution, e.g. transition metal dissolution. Forexample, the concentration of the one or more oxidizing agents can be atleast about 50 mg/L, typically in a range from about 50 mg/L to about1,000 mg/L.

One or more chelating agents, such as citric acid or ammonia, also canbe present in the byproduct slurry stream to be treated, typically tofacilitate maintaining one or more transition metals therein insolution. The slurry wastewater stream can also have solids orparticulates, typically sized in a range from about 0.001 to about at alevel or concentration from about 500 to about 5,000 mg/L (about 500 toabout 5,000 ppm) or even up to 20,000 ppm. Complexing agents, such asgluconates, tartrates, citric acid, and ammonium hydroxide, thatfacilitate etching or enhancing the corrosion rate of transition metals,such as copper, may also be present in the CMP slurry stream. Table 1lists common CMP slurry stream constituent as well as their typicalconcentrations.

TABLE 1 Typical CMP Slurry composition. Constituent ConcentrationDissolved copper 5-100 mg/L Total solids 500-5,000 mg/L Oxidizing agents50-1,000 mg/L Etchants 200 mg/L Complexing agents 10-400 mg/L DI waterbackground 99%+ pH 6 to 7

Notably, ion exchange media suppliers and equipment manufacturersencourage particulate material removal ahead, i.e., upstream, of ionexchange and carbon systems and emphasize that solids removal operationsform an essential aspect of pretreatment systems because particles canbind and block the active media and operate as a particulate filter.Consequently, without removal thereof, the suspended solids undesirablyaccumulate resulting in an increase in pressure drop across the resinand/or carbon bed. The increased pressure drop typically further resultsin channeling phenomena, wherein the fluid stream to be treated isdirected to a flow path of least resistance, effectively circumventingat least a portion of the bed, limiting the contact to the bulk of theprocess fluid. This results in high contaminant leakage and pooreffective bed capacity. The suspended solids and colloidal matter canalso coat the ion exchange media, reducing the rate of diffusion of theionic species to and from media. Indeed, ion exchange mediamanufacturers further proscribe pre-treating the stream to be treated toremove or neutralize soluble constituents that degrade the ion exchangemedia. Such species include, for example, oxygen, ozone, chlorine,hydrogen peroxide and other oxidants or oxidizing species or agents.Thus, prior art systems utilizing ion exchange media include one or morepre-treatment unit operations that remove such particulates and/oroxidizing species.

The systems and techniques of the invention, in contrast, inventivelyeliminates, if not reduces, the reliance on such additional complexitiesin treating particulate streams, which may also contain one or moreoxidizing species.

In accordance with one or more aspects, the ion exchange media utilizedin the systems and techniques of the invention comprises, consistsessentially of, or consists of one or more materials that can form orpromote formation of one or more chelate complexes with the one or moretarget species. For example, the ion exchange media can comprise one ormore functional groups that can form one or more ligands or complexeswith one or more metal species. Thus, in accordance with some aspects ofthe invention, the ion exchange media comprises one or more ligands orchelating moieties, typically as a pendant group on a substrate. The oneor more functional groups can have any suitable functionality that canbind or immobilize one or more target species thereby effecting removalfrom a carrying fluid or fluid to be treated, or at least a reduction ina concentration thereof. Thus during treatment operations, the one ormore target species can be bound or otherwise secured to the ionexchange media material through the one or more functional groups. Theone or more pendant groups can be supported on a polymer, or othersupporting media, that comprises the ion exchange media material. Thus,the ion exchange media can comprise a first region having a firstfunctionality and a second region having a second functionality.Further, the ion exchange media can comprise any number or types of suchfunctional groups at various concentrations or densities thereof thatprovides a desired loading capacity. Thus, for example, the ion exchangemedia can have a first region comprising a functional group at a firstdensity or concentration, typically on a volume basis, and one or moresecond regions comprising a second functional group at a second region,or other density or concentration. The first and second regions candiffer in one or more aspects to provide flexibility in capturing one ormore target species but can comprise the same functional group.

In accordance with one or more embodiments, the systems and techniquesof the invention can provide a method of removing or at least reducingthe concentration of copper ions. The method comprises contacting astream containing copper ions with a treatment system comprising,consisting essentially of, or consisting of an ion exchange bedcomprising complexing ion exchange media, preferably without performingprior removal of solids or particulates and/or prior removal orreduction of oxidizing species by catalytic exposure to carbon.Contacting the stream can involve introducing the stream into one ormore ion exchange beds in a downward flow direction or in an upward flowdirection.

The invention can pertain to pretreatment systems that involve nochemical addition. For example, the pretreatment system can neutralize,remove, or at least reduce the concentration of any oxidizer that may bepresent in the stream to be treated. For example, the pretreatmentsystem can introduce energy that facilitates reduction of the oxidizer.Non-limiting examples of such pretreatment systems include, but are notlimited to, electrochemical, photochemical, and thermochemicaltechniques.

Electrochemical techniques can utilize one or more electrochemical cellscomprising an anode and cathode (electrodes) connected to an electricalsource to introduce an electrical current into a liquid. The cell can beconfigured as a batch tank, a flow through pipe, or other configurationin which the solution containing the oxidizer comes into electricalcommunication with the electrodes. In such an arrangement, one or moreof the electrodes is depleted of electrons, which are transferred to theother electrode through the external connection. Reduction reactions canoccur at the cathode and oxidation reactions can correspondingly occurat the anode. Supplied current as, for example, a direct current istypically controlled by a rectifier. The amount of current, amperage,used can depend on several factors or condition such as the solutioncharacteristics and/or the concentration and type of pertinent chemicalspecies, and the rate at which reduction is performed or desired.

Photochemical techniques typically provide an actinic radiation thatpromotes one or more reactions. For example, the photochemicaltechniques can utilize ultraviolet radiation to promote one or morereduction reactions.

Thermochemical techniques can involve heating a solution containing anoxidizer to a temperature which promotes decomposition of the oxidizingspecies. For example, for copper CMP slurry wastewater, the temperaturecould be up to and including the water boiling point (about 100° C.). Atthe elevated temperature, reactions, including the rate of reduction ordecomposition reactions typically increase thus promoting thedestruction of the one or more oxidizing species.

The complexing ion exchange media typically comprises at least onecomplexing or chelating functionality. The functionality comprises anygroup, typically a multidentate group, which forms a complex with thetarget species. For example, the ion exchange media can comprise animinodiacetic functional group on a polymeric backbone. Other functionalgroups that can be utilized in accordance with one or more embodimentsof the invention, include, but are not limited to, polyamine,bispicolylamine, and aminophosphonic groups. The selection of thefunctional group may depend of several factors including, for example,the affinity for a target species. Thus, for example, the selection ofthe one or more functional groups to be utilized may depend on thetarget metal species, e.g. a transition metal, which can be any one ormore of copper, lead, nickel, zinc, cobalt, cadmium, iron, tantalum,silver, gold, platinum, palladium, iridium, rhodium, ruthenium,manganese, tungsten, and hafnium and/or gallium.

As exemplarily shown in FIG. 1, one or more collection tanks 30 may beutilized to collect one or more streams to be treated from one or moreCMP systems 20 prior to processing in a treatment system 40. Optionally,an acid or a base (not shown) may be introduced to adjust a pH of thestream to be treated.

In some cases, the treatment system can comprise two or more ionexchange beds arranged in parallel or in series, or combinationsthereof. For example, the treatment system can comprise two trains eachcomprising a first ion exchange bed and a second ion exchange beddownstream of the first bed. The first ion exchange be can be consideredas the primary bed, typically removing or reducing the concentration ofthe target metal species in the slurry stream and the second, downstreamion exchange bed can be considered as the polishing bed that removes anyresidual target species. The primary and polishing beds may beinterchanged as necessary. For example, the primary bed can be replacedafter a predetermined period or upon a detection of an unacceptablecondition, or concentration of one or more target species in the exitingstream. The polishing bed can then be placed in the primary position,and a freshly regenerated column can be placed at the polishingposition. The spent ion exchange bed can be reconditioned and/orregenerated.

The ion exchange media typically comprises a chelating functionalitypendent on a cross-linked polymer backbone. The supporting substrate orbackbone of most ion exchange resins is typically composed of longchains of polystyrene. Resin manufacturers typically improve thestrength and to render the resins insoluble in water and/or non-aqueoussolvents, polystyrene chains are typically reacted with a crosslinkingagent such as divinyl benzene (DVB). The reaction typically joinsmultiple chains of polystyrene together through one or more links.Oxidizers attack and destroy not only the functional pendant groups onthe resin but also attack and destroy the DVB links. All oxidizersattack both the functional group and the DVB crosslinks. As more DVBcrosslinks are destroyed, the resin absorbs and swells with water andsoftens. In use, the softened resin will expand and squeeze togetherwhich will prevent or inhibit fluid flow therethrough. Some oxidizingspecies are more aggressive than others and higher oxidizerconcentration accelerates the rate of deterioration. Other conditions,such as low or high pH, heat, and the presence of catalysts alsoaccelerates the rate of deterioration. In some cases, transition metalslike copper can catalyze oxidative degradation of resin especially underacid conditions. Typically, the chelating ion exchange media can have anoperating capacity in the range of about 1.5 to 2.0 pounds or more ofmetal per cubic foot.

The ion exchange media typically has a maximum uniformity coefficient ofabout 1.7. The ion exchange resin of the process and apparatus of thepresent invention is screened to control bead size. The ion exchangeresin of the process and apparatus of the present invention can have theproperties listed in Table 2.

Treated slurry stream exits the treatment system in a state that issuitable for discharge as discussed above. Optionally, the treatedstream can be further treated in one or more post-treatment systems (notshown). For example, solids may be removed therefrom in one or morefiltering unit operations or systems, typically after or downstream ofthe ion exchange and/or carbon unit operations. One or more agents, suchas coagulating and/or flocculating agents, may be utilized to improvethe one or more post-treatment processes. Examples of other unitoperations that can be utilized in the post-treatment system include,but are not limited to, reverse osmosis processes and other systems andtechniques that can further reduce other target species from the stream.

TABLE 2 Typical properties of ion exchange resin. Characteristic ValueBead size min. 90% 0.4-1.23 mm Effective size 0.55 mm Uniformitycoefficient 1.7 Bulk weight (+/−5%) 800 g/L Density 1.18 g/ml Waterretention 50-55 wt % pH range 0-14 Functional group iminodiaceticStructure macroporous Matrix cross-linked polystyrene Minimum Capacity2.2 eq/L in H⁺ form

Regeneration of the laden, typically saturated, ion exchange media maybe effected by utilizing one or more mineral acids, such as sulfuricacid, to remove the complexed metal species. Hydrochloric acid may beadvantageously utilized in some cases.

EXAMPLES

The function and advantages of these and other embodiments of theinvention can be further understood from the examples below, whichillustrate the benefits and/or advantages of the one or more systems andtechniques of the invention but do not exemplify the full scope of theinvention.

In the examples, copper in solution was measured according to StandardMethods 3120 B, Metals by Inductively Coupled Plasma (ICP) Method or3125 B, Inductively Coupled Plasma/Mass Spectrometry (ICP/MS) Method(1998, 20^(th) Ed.).

Solids levels were measured according to U.S. EPA Method 160.3.

Hydrogen peroxide concentration was measured by direct titration withstandardized potassium permanganate reagent.

The ion exchange resin utilized was LEWATIT® TP207 weakly acidic,macroporous ion exchange resin with chelating iminodiacetate groups,which was acquired from Sybron Chemicals Inc., a LANXESS Company,Birmingham, N.J.

Example 1 Performance of Ion Exchange Resin Exposed to an Oxidizer

In this example, a treatment system in accordance with one or moreembodiments of the invention including an ion exchange column utilizinga chelating ion exchange resin was exposed to an oxidizer. The effectivecapacity of the exposed ion exchange resin was used to characterizedeterioration and effect on its performance.

The treatment system is schematically shown in FIG. 2. The systemconsisted essentially of an ion exchange column 210 including ionexchange resin therein. A pump 214 was used to withdraw acopper-containing solution from a source or feed tank 212 and introduceinto ion exchange column 210. An effluent holding tank 216 was utilizedto collect the treated fluid from ion exchange column 210. Norecirculation of the solution was performed so that the ion exchangematerial was exposed to a solution having the same initial and finalcopper concentration. Prior to the first run, the resin waspreconditioned by hydrating it for at least twenty-four hours indeionized water, then converting it fully to the acid form by exposurean about 10% hydrochloric acid solution.

The ion exchange column had a resin bed that was about 1.5 cm indiameter and was about 16 cm deep.

Several runs were performed by exposing the resin bed to variousoxidizer-containing solutions. The solution was also comprised of about40 mg/L of copper species, as a salt of the sulfate. Exposure wasperformed by passing the various solutions through the ion exchangecolumn for about eight hours and holding at a dormant, non-flowingcondition for about sixteen hours of each day. The pH of the solutionwas adjusted to be about 3 pH units by adding sufficient sulfuric acid.

The oxidizer used was hydrogen peroxide at the various concentrationlevels noted in Table 3. Table 3 further lists the measured capacity ofthe ion exchange bed after exposure at various time intervals duringexposure. The capacity of the bed was normalized relative to unexposedresin. Specifically, ion exchange resin not exposed to an oxidizer wasdesignated as having a capacity of 1.0 and the resin capacity duringexposure was designated relative to the unexposed capacity. Thus, forexample, oxidizer-exposed ion exchange resin having a capacity that wasdetermined to be about half of the unexposed resin was designated ashaving a capacity of about 0.5. Determination of resin capacity can beperformed by relative saturation. For example, the resin can be strippedof the metal by regeneration with an about 10% hydrochloric acidsolution. About two liters of a copper sulfate solution, containingabout 3,000 mg Cu/L, is passed through about 25 ml of resin tocompletely exhaust the ion resin exchange sites with copper species.Excess copper solution is rinsed from the resin. The copper is strippedfrom the resin with about 0.5 L of an about 10% hydrochloric acidsolution. This strip solution is captured and analyzed for total coppercontent. The amount of copper determined therein relates directly to thenumber of usable exchange sites per unit volume of ion exchange resin(virgin resin being assigned a value of 1.0). It is believed thatexposure to oxidizing species or reagents renders some exchange sitesunusable so the amount of copper that can be loaded per unit volume ofresin typically decreases with degradation. Compared to virgin resin,therefore, the value is less than 1.0 for oxidizer-exposed resins.

The data in Table 3 show that the capacity of the ion exchange resin candegrade with prolonged exposure. Further, the rate of degradationaccelerated at higher oxidizer concentrations.

TABLE 3 Effect of Oxidizer Exposure on Iminodiacetate Resin. ExposureH₂O₂ Concentration Time (mg/L) (hours) 0 50 100 500 1,000 0 1 1 1 1 1264 1 1 384 1 1 1 552 1 0.94 672 0.99 0.97 0.89 936 1.03 0.86 0.77 10560.99 0.99 1320 1 0.94 0.91 0.82 0.71 1560 0.99 0.7 0.58 1584 0.94 0.881776 1.01 0.95 0.91 0.66 0.51 1968 0.92 0.88 2016 0.98 0.58 0.43 22560.52 0.38 2280 0.92 0.86 2496 0.87 0.83 2784 0.89 0.82 3144 0.88 0.803384 0.82 0.75

Example 2 Performance of Ion Exchange Resin When the Oxidizer isChemically Neutralized

In this example, a treatment system in accordance with one or moreembodiments of the invention comprising an ion exchange column withchemical neutralization of an oxidizer was evaluated for metal treatmentcapacity. The treatment system is schematically shown in FIG. 2 and hasbeen substantially described in Example 1. The neutralizing or reducingagent was sodium metabisulfite. However, other reducing agents such assodium bisulfite and sodium sulfite, can be utilized. The neutralizationof hydrogen peroxide with sodium sulfite, sodium bisulfite, or sodiummetabisulfite results in formation of sodium sulfate (Na₂SO₄). Theinitial concentration, prior to neutralization, of hydrogen peroxide inthe solution to be treated is listed in Table 4. The resultantconcentration of sodium sulfate product is also listed. The initialconcentration of metal species, copper (sulfate), for each test runsolution was about 40 mg/L. The starting pH of each solution was about 3pH units.

The ion exchange column had a resin bed that was about 1.5 cm indiameter and was about 16 cm deep.

Citric acid was included as an organic chelator for copper and istypically used in copper CMP slurry formulations. It typically complexesthe copper ions produced during a copper CMP process so thatprecipitation and/or re-absorption onto the semiconductor surface ofsuch species are inhibited. Organic chelators bind copper to varyingdegrees. Typically, the stronger the force binding copper in thechelate, the more difficult it is for ion exchange resins to remove thecopper from the chelate and take it up on the ion exchange resin. Highsalt background can also impair copper sorption from the solution ontothe resin, in this case by high ionic background. When chemical reducingagents, like sodium bisulfite, are used to chemically decomposeoxidizers, like hydrogen peroxide, the resulting chemical reactionincreases the total solution ionic background. Specifically, thereaction between sodium bisulfite and peroxide can yield sodium andsulfate ions in solution. The higher the oxidizer concentration, themore bisulfite is required to neutralize and, therefore, the greater theresulting ionic background.

Table 4 lists the number of equivalent bed volumes (BV) passed throughthe resin bed before effluent therefrom was found to be about 30 mg/L,designated as breakthrough condition, or about 75% of the influent metalconcentration. Table 4 compares copper loading on the ion exchange forthree cases. The “Blank”, or baseline, case shows copper loading when nochelator (e.g. citric acid) is present and with only a small ionicbackground loading. The “Citric” case shows copper loading when anamount of a chelating agent, citric acid, at a level typically presentin copper CMP wastewater, is added to the baseline. In this case, littleadditional ionic background results since citric acid is only partiallyionized in solution. The “Sulfate” case shows copper loading when theionic background is significantly increased in the absence of citricacid. The amount of sodium sulfate salt is equivalent to that formed ifabout 1,100 ppm of hydrogen peroxide were removed by sodium bisulfite(in the other two cases, the amount is equal to removal of about 200 ppmof the peroxide). The results show that the citric acid and sulfatecases are essentially the same as the baseline case and the increase inbackground ionic loading by use of a chemical reducing agent has noappreciable negative impact on copper removal by the ion exchange resin,regardless of whether citric acid is present.

TABLE 4 Effect of High Sulfate Exposure. Test Solution CompositionCopper (mg/L) 40 40 40 BTA (mg/L) 500 500 500 Na₂SO₄ (mg/L) 800 8004,500 Citric Acid (mg/L) 0 500 0 pH 3 3 3 H₂O₂, before treatment (mg/L)200 200 1,000 BV Breakthrough (to about 30 mg/L) Run “Blank” “Citric”“Sulfate” 1 2,000 1,920 2,140 2 1,900 1,640 2,320 3 2,080

BTA is 1,2,3-benzotriazole. BTA is an “alkyl/aryl triazolesanti-tarnish” component that is typically present copper CMP slurryformulations. BTA typically prevents copper oxide formation on thepolished copper remaining on the semiconductor device during and afterCMP processes.

Example 3 High Total Solids Streams

This example shows the performance of a treatment system in accordancewith one or more embodiment of the invention in treating a slurry streamfrom a CMP process. Evaluation was performed for about twenty days. Thistest also shows the effectiveness of copper uptake by the resin even inthe presence of an oxidizer.

The system, schematically illustrated in FIG. 3, was comprised of an ionexchange column 310 downstream of a carbon column 311. A pump 312 wasutilized to drive a CMP solution from a feed tank 314 through carboncolumn 311 and ion exchange column 310. A sample point 316 was disposedbetween carbon column 311 and ion exchange column 310. Treated fluidfrom ion exchange column 310 was collected in collection tank 318.

The system was operated about eight to twelve hours per day, shut downat the end of each day and restarted the next day. After twelve days,ion exchange testing was stopped and hydrogen peroxide removal by carboncontinued for an additional eight days. Flow of the slurry feed solutionthrough the carbon and ion exchange tanks was even and steady throughoutthe test, indicating no solids build up on either media. Examination ofthe media at the conclusion of the test showed no slurry solidsaccumulation in either media.

Simulated copper CMP slurry wastewater was prepared. Aliquots ofcommercially manufactured copper CMP slurry concentrate were diluted tothe total solids test conditions. The slurry solution was prepared bydiluting commercially available copper CMP slurry and adding hydrogenperoxide and copper sulfate to simulate copper CMP slurry wastewater.Calculated amounts of copper sulfate (as crystalline technical gradeCuSO₄.5H₂O) from Chem One Ltd., Houston, Tex., and hydrogen peroxide(about 30% H₂O₂, electronics grade) from Ashland Specialty Chemical,Dublin, Ohio, were added to the influent slurry solution. The hydrogenperoxide concentrations of the slurry stream in and out of the ionexchange resin bed are listed for each day in Table 5. Similarly, theinlet and outlet copper concentrations along with the solids inletconcentration are also correspondingly listed. The pH was adjusted toabout 3 pH units by adding sulfuric acid. Particle size of the solidswas in the range of from about 0.001 μm to about 1 μm.

Ion exchange column 310 had a resin bed that was about 8 inches indiameter and was about 40 inches deep. Carbon column 311 was about 14inches in diameter and was about 40 inches deep. The carbon utilized wasCENTAUR® granular activated carbon, available from Calgon CarbonCompany, Pittsburgh, Pa.

Samples were retrieved and analyzed at the indicated hours listed inTable 5. The data in Table 5 shows that even with total solids loadingof up to about 4,500 mg/L, copper can still be removed. Further, theremoval of hydrogen peroxide need not be performed for effective copperremoval as shown by the results from runs performed on days 4, 5, and 7.The total solids in the test in Table 5 are largely from the slurryparticulate solids themselves, i.e., the silica and alumina used forgrinding and polishing. Very little of the solids are from dissolvedions like copper and sulfate.

TABLE 5 Effect of High Total Solids. H₂O₂ Cumulative ConcentrationCopper Solids Run Run (mg/L) Concentration Concentration, Time Time POST(mg/L) IN Day (hours) (hours) IN CARBON IN OUT (mg/L) 1 1 8 524 <0.326.2 0.052 3,370 8 NA <0.3 26 0.033 3,680 2 1 16 NA 28.6 0.024 3,450 8520 <0.3 29.8 0.046 4,515 3 1 24.5 450 27.6 0.032 3,360 8.5 520 <0.327.2 0.027 3,180 4 1 32.5 384 29 0.025 4,000 8 NA 17 28.5 0.027 3,750 51 40.5 428 4 29.3 <0.04 3,785 8 410 16.4 31 <0.04 3,980 6 1 48.5 377<0.3 27.1 0.114 3,870 8 402 <0.3 27.7 <0.04 3,420 7 1 60.5 610 3.5 28.6<0.04 3,930 12 493 <0.3 25.4 <0.04 3,580 8 1 72.5 503 <0.3 25 <0.043,540 12 463 <0.3 31.5 0.053 4,090 9 1 84.5 510 <0.3 28.7 <0.04 3,760 12517 <0.2 26.9 0.156 3,400 10 1 96.5 500 <0.3 27.1 0.079 3,350 12 524<0.2 23.2 0.124 2,840 11 1 108.5 525 <0.3 27.1 0.127 3,420 12 502 <0.227.1 0.167 3,790 12 1 120.5 563 <0.2 27.6 0.08 3,800 12 510 <0.2 25.11.61 3,480 13 1 129 428 4 ~3,500 8.5 410 16.4 ~3,500 14 1 137.3 377 <0.3~3,500 8.3 402 <0.3 ~3,500 15 1 146.1 610 3.5 ~3,500 8.8 493 <0.3 ~3,50016 1 155.1 503 <0.3 ~3,500 9 463 <0.3 ~3,500 17 1 163.6 510 <0.3 ~3,5008.5 517 <0.2 ~3,500 18 1 171.8 500 <0.3 ~3,500 8.2 524 <0.2 ~3,500 19 1180.6 525 <0.3 ~3,500 8.8 502 <0.2 ~3,500 20 1 189.6 563 <0.2 ~3,500 9510 <0.2 ~3,500

Example 4 Hydrogen Peroxide Removal with Carbon and Filter Media

In this example, a waste slurry stream from a CMP process was treated ina treatment system comprising a pretreatment subsystem. The treatmentsystem, substantially shown in FIG. 3, was comprised of a pretreatmentsystem 311, which was a carbon column or a filter media column, and anion exchange column 310. A pump 312 was utilized to introduce thesolids, oxidizer, and copper containing solution from feed tank 314.Treated slurry was collected and sampled in a collection tank 318.

Hydrogen peroxide in the slurry stream was removed and/or neutralized byutilizing the pretreatment system having CENTAUR® granular activatedcarbon, available from Calgon Carbon, Company, Pittsburgh, Pa., or withBIRM® granular filter media, available from Clack Corporation, Windsor,Wis. The CENTAUR® granular activated carbon system consisted essentiallyof a column about 8 inches in diameter and about 40 inches deep. TheBIRM® granular filter media subsystem consisted essentially of a columnabout 8 inches in diameter and about 20 inches deep. For each of theruns, the corresponding ion exchange column had about the samedimensions as the respective carbon or filter media columns.

The influent and post treatment copper total solids and hydrogenperoxide concentrations in the slurry stream are listed in Tables 6 and7. The data shows that both pretreatment systems can reduce or removehydrogen peroxide concentration and that copper species was effectivelyremoved by the ion exchange column.

TABLE 6 Oxidizer Removal by Granular Activated Carbon. CopperConcentration Total Solids H₂O₂ Elapsed (mg/L) (mg/L) (mg/L) Time POSTPOST POST POST Sample (hours) IN RESIN IN CARBON RESIN IN CARBON 1 030.8 0.018 2,920 2,100 1,660 204 <1 2 1.5 31.8 0.043 2,810 3,170 2,580198 <2.6 3 3.5 32.5 <0.016 2,520 2,605 2,400 204 <1.3 4 5.5 31.4 0.0212,510 2,550 2,390 185 <1.4 5 7.5 34.6 0.021 2,680 2,640 2,550 209 <1

TABLE 7 Oxidizer Removal by Granular Filter Media. Copper ConcentrationTotal Solids H₂O₂ Elapsed (mg/L) (mg/L) (mg/L) Time POST POST POST POSTSample (hours) IN RESIN IN BIRM ® RESIN IN BIRM ® 1 0 28.3 0.186 2,9203,430 2,510 214 95 2 1.5 29.2 0.322 2,750 2,910 2,750 NA 88 3 3.5 29.50.844 2,870 2,890 2,840 NA 108 4 5.75 30.6 2.87 2,820 2,895 2,840 NA 1615 7.75 30.5 2.84 2,790 2,810 2,840 201 170 (NA = not analyzed)

Example 5 Performance of Ion Exchange Varying Total Solids and HydrogenPeroxide Concentration

Slurry wastewater obtained from a commercial copper CMP process was usedto evaluate oxidizer and metal removal by a pretreatment subsystem witha carbon bed and a treatment system with two ion exchange beds asschematically illustrated in FIG. 4. The carbon bed 510 was comprised ofabout 3.6 ft³ CENTAUR® granular activated carbon and the ion exchangebeds 512 and 514 were each comprised of about 3.6 ft³ LEWATIT® TP207weakly acidic, macroporous ion exchange resin with chelatingiminodiacetate groups. The slurry fluid was introduced from feed tank516 into the system by utilizing pump 518. Total solids, hydrogenperoxide, and copper concentrations were adjusted to the values shown inTable 8 using supplied raw copper slurry, about 30% hydrogen peroxide,from Ashland Specialty Chemical, and copper sulfate pentahydrate, fromChem One Ltd. The pH was adjusted to the levels shown in Table 8 byadding an about 25% sulfuric acid solution, diluted at a ratio of about1:1 with deionized water. The treated stream from ion exchange columns512 and 514 were collected in collection tank 520.

Sample for analysis were retrieved at sample point 522 and at collectiontank 520. Table 8 lists the inlet and properties of the slurry fluid forvarious test runs. The data show that copper was effectively removedeven without the removal of hydrogen peroxide by the activated carbonsubsystem as noted in test numbers 2, 4, 5, and 10. The data also showthat treatment can be effected even on slurry streams having solids upto about 20,000 ppm. Indeed, at a solids loading of nearly 20,000 ppm,the effective metal removal still exceeds 90%, thus the data indicatethat the invention may still be practiced with slurry streams greaterthan 20,000 ppm.

TABLE 8 Hydrogen Peroxide and Copper Removal. Flow Total Copper H₂O₂Test Rate Solids Copper H₂O₂ Removed Removed Number pH (gpm) (mg/L)(mg/L) (mg/L) (%) (%) 1 3 3.5 12,795 54.9 64.6 99.6 100 2 4 5.4 6,0448.98 43.8 99.4 8.7 3 2 1.6 8,532 9.02 1,632 98.1 94.6 4 4 1.6 4,932 97.6672 100 88.6 5 4 5.4 15,240 84.5 2,074 99.3 51.6 6 2 5.4 6,140 87.3 66399.5 100 7 3 3.5 10,305 42.8 1,887 99.5 100 8 3 3.5 10,630 45.3 1,80299.2 100 9 2 1.6 17,750 83 476 99.7 96.4 10 2 5.4 19,180 7.39 2,142 96.374.9 11 4 1.6 18,240 8.86 536 99.1 100

Example 6 Photochemical Pretreatment by Electromagnetic Irradiation

In this example, removal or reduction of hydrogen peroxide from atypically CMP slurry stream was effected by techniques having nochemical addition. The nonchemically-based oxidizer reduction waseffected by a pretreatment system based on photochemical reductioninvolving exposure to ultraviolet (UV) electromagnetic radiation assubstantially illustrated in FIG. 5.

The pretreatment system 610 utilized a Model # AMD150B1/3T UV assembly,from Aquionics Inc., Erlanger, Kentucky, with an about 1.6 gallonvolumetric capacity UV cell 612 having a 185 nm wavelength, model #130027-1001 medium pressure UV lamp 613. The lamp was operated at about1 KW and powered by a power source 614. The solution to be treated,prepared as substantially described below, was pumped through the mediumpressure UV cell 612 from a feed tank 616 using a pump 618 at a flowrate of about 0.75 gpm. The applied dosage of UV radiation at this flowrate was about 4,000 microwatt-sec/cubic centimeter. The irradiatedfluid was collected in a collection tank 620.

The slurry stream was comprised of a mixture of silica-based andalumina-based commercially available copper CMP slurry concentratesdiluted in deionized water in a ratio of about 1:1:40. The pH of theslurry stream was adjusted to about 3 pH units with sulfuric acid. Ametal species was added to the slurry stream as copper sulfatepentahydrate. The oxidizer was added to the solution using a calculatedaliquot of about 30% electronics grade hydrogen peroxide. Theconcentrations of the oxidizer and metal species prior to treatment arelisted in Table 9. The data show that a pretreatment system comprisingUV radiation techniques can reduce the oxidizer concentration.

These tests did not use ion exchange resin but focused onphotochemically removing or reducing the concentration of oxidizingspecies. However, as shown in the tests in the above examples, the metalspecies, copper, would have been effectively removed by utilizing one ormore embodiments of the treatment system of the invention.

It is expected that the higher UV dosage levels, longer retention timein the UV cell, and other techniques can further improve oxidizerspecies reduction; however, as noted in the examples above, especiallywith respect to Examples 4 and 5, it is not necessary to remove all theoxidizer species to achieve metal removal.

TABLE 9 Hydrogen Peroxide Decomposition by Irradiation. Flow TotalInfluent Influent Rate Solids H₂O₂ Copper H₂O₂ Test pH (gpm) (mg/L)(mg/L) (mg/L) Reduction (%) 1 6.6 0.75 3,500 470 30 15 2 3 0.75 3,500300 30 33 3 3 0.75 3,500 200 30 18

While the invention has been described in conjunction with severalembodiments, it is to be understood that many alternatives,modifications, and variations will be apparent to those skilled in theart in light of the foregoing description. Accordingly, this inventionis intended to embrace all such alternatives, modifications, andvariations which fall within the spirit and scope of the appendedclaims.

Having now described some illustrative embodiments of the invention, itshould be apparent to those skilled in the art that the foregoing ismerely illustrative and not limiting, having been presented by way ofexample only. Numerous modifications and other embodiments are withinthe scope of one of ordinary skill in the art and are contemplated asfalling within the scope of the invention. In particular, although manyof the examples presented herein involve specific combinations of methodacts or system elements, it should be understood that those acts andthose elements may be combined in other ways. For example, the inventioncontemplates the utilization of fluidized bed or similar unit operationswherein the ion exchange media is effectively fluidized by appropriatelyintroducing the fluid to be treated at one or more bottom ports at asufficient flow velocity.

Further, acts, elements, and features discussed only in connection withone embodiment are not intended to be excluded from a similar role inother embodiments. It is to be appreciated that various alterations,modifications, and improvements can readily occur to those skilled inthe art and that such alterations, modifications, and improvements areintended to be part of the disclosure and within the spirit and scope ofthe invention.

Moreover, it should also be appreciated that the invention is directedto each feature, system, subsystem, or technique described herein andany combination of two or more features, systems, subsystems, ortechniques described herein and any combination of two or more features,systems, subsystems, and/or methods, if such features, systems,subsystems, and techniques are not mutually inconsistent, is consideredto be within the scope of the invention as embodied in the claims.

Use of ordinal terms such as “first,” “second,” and the like to modify aclaim element does not by itself connote any priority, precedence, ororder of one element over another or the temporal order in which stepsor acts of a method are performed, but are used merely as labels todistinguish one element having a certain name from another elementhaving a same name (but for use of the ordinal term) to distinguish theelements.

Those skilled in the art should also appreciate that the parameters andconfigurations described herein are exemplary and that actual parametersand/or configurations will depend on the specific application in whichthe systems and techniques of the invention are used. Those skilled inthe art should also recognize or be able to ascertain, using no morethan routine experimentation, equivalents to the specific embodiments ofthe invention. It is therefore to be understood that the embodimentsdescribed herein are presented by way of example only and that, withinthe scope of the appended claims and equivalents thereto; the inventionmay be practiced otherwise than as specifically described.

1. A method of treating a slurry stream comprising: providing the slurry stream comprising at least one metal and at least one oxidizer present at a concentration of at least about 50 mg/L; and introducing the slurry stream into an ion exchange column.
 2. The method of claim 1, wherein the ion exchange column comprises ion exchange material comprising at least one complexing group.
 3. The method of claim 1, wherein the ion exchange column comprises ion exchange material comprising at least one pendant functionality selected from the group consisting of iminodiacetate, polyamine, bispicolylamine, and aminophosphonic.
 4. The method of claim 2, wherein the ion exchange material comprises an iminodiacetate functional group.
 5. The method of claim 2 wherein the oxidizer concentration is less than 1,500 mg/L.
 6. The method of claim wherein the oxidizer comprises at least one species selected from the group consisting of iodates, periodates, bromates, perbromates, chlorates, perchlorates, peroxygen compounds, nitrate compounds, persulfate compounds, permanganate compounds, and chromate compounds.
 7. The method of claim 6, wherein the oxidizer comprises at least one compound selected from the group consisting of nitric acid, hydrogen peroxide, ferric nitrate, and ammonium persulfate.
 8. The method of claim 1, wherein the at least one metal comprises a metal selected from the group consisting of copper, lead, nickel, zinc, cobalt, cadmium, iron, tantalum, silver, gold, platinum, palladium, iridium, rhodium, ruthenium, gallium, manganese, tungsten, hafnium, and mixtures thereof.
 9. The method of claim 8, wherein the at least one metal is copper.
 10. The method of claim 1, wherein the particulate material has a diameter in a range of 0.001 μm to 1 μm.
 11. The method of claim 1, wherein the concentration of the particulate material in the slurry stream is in a range of 50 mg/L to 20,000 mg/L.
 12. (canceled)
 13. The method of claim 1, further comprising a step of neutralizing at least a portion of the at least one oxidizer.
 14. The method of claim 13, wherein the step of neutralizing comprises adding at least one reducing species to the slurry stream.
 15. The method of claim 13, wherein the step of neutralizing comprises chemically, electrochemically, photochemically, or thermochemically rendering the oxidizer inactive.
 16. (canceled)
 17. A treatment system for treating a slurry stream comprising at least one metal, at least one oxidizing species present at a concentration of at least 50 mg/L and solids at a concentration in a range front 50 mg/L to 20,000 mg/L, the treatment system comprising: an inlet fluidly connected to a source of the slurry stream; and means for reducing the concentration of the at least one metal from the slurry stream.
 18. The treatment system of claim 17, wherein the at least one metal is a metal selected from the group consisting of copper, lead, nickel, zinc, cobalt, cadmium, iron, tantalum, silver, gold, platinum, palladium, iridium, rhodium, ruthenium, gallium, manganese, hafnium, and tungsten.
 19. The treatment system of claim 17, wherein the at least one oxidizer is a species selected from the group consisting of hydrogen peroxide, ferric nitrate, and ammonium persulfate.
 20. The treatment system of claim 17, further comprising means for neutralizing the at least one oxidizer.
 21. The treatment system of claim 20, wherein the means for neutralizing the at least one oxidizer electrochemically, photochemically, and/or thermochemically reduces a concentration of at least one oxidizer.
 22. The treatment system of claim 17 wherein the means for reducing the concentration of the at least one metal from the slurry stream comprises an ion exchange column having media with at least one functional group capable of forming a complex with the at least one metal.
 23. (canceled)
 24. A treatment system for treating a slurry stream comprising at least one metal and at least one oxidizing species, the treatment system consisting essentially of: an electrochemical, photochemical or thermochemical pretreatment unit; and at least one ion exchange column fluidly connected downstream of the pretreatment unit.
 25. The system of claim 24, wherein the ion exchange column contains ion exchange media comprising at least one pendant functional group capable of forming a complex with the at least one metal.
 26. The system of claim 25, wherein the at least one pendant functional group comprises an iminodiacetic functional group.
 27. The system of claim 24, wherein the at least one metal is selected from the group consisting of copper, lead, nickel, zinc, cobalt, cadmium, iron, tantalum, silver, gold, platinum, palladium, iridium, rhodium, ruthenium, gallium, hafnium, manganese, and tungsten.
 28. The system of claim 24, wherein the at least one oxidizing species is present at a concentration of at least about 50 mg/L.
 29. The system of claim 24, wherein the slurry stream comprises particulate matter in a range of about 50 mg/L to about 20,000 mg/L.
 30. The system of claim 24, wherein the ion exchange column comprises ion exchange material comprising a cross-linked polystyrene substrate.
 31. The system of claim 1, wherein the ion exchange column comprises ion exchange material comprising a cross-linked polystyrene substrate. 